I also suggest pointing the SPL meter toward the screen at ear level (use a tripod). I find it more accurate reflects what you'll hear (unless your audio canals point straight up out of your head) when you're sitting facing the screen.

Ro, basically you can rely on MCACC on your Pioneer to accurately set the speaker levels. There's no good reason to expect that a manual setting using the RS meter will be more accurate. That meter isn't a precision instrument(they claim +/-2dB accuracy)and the element of human error can also affect a manual calibration, so if the results differ it shouldn't be assumed that the manual results are more nearly correct.

If you do use the manual setting process, follow the instructions in your receiver's manual. Generally receiver tones are at 75dB and the receiver volume setting is at 0 for the calibration. Then if you desire listening at that "reference level"(usually too loud)you'd have the receiver volume control at 0, where it was for the calibration.